TMC
Sorry it took so long to reply, I've been off the net for a while.
AOWs may be purchased by civilians as long as it is legal in your state. The $5 tax is paid to the U.S. Treasury and accompanies your application to the ATF.
Suggest you post a WTB (want-to-buy) add for an AOW shotgun on Tom Bowers' board. You'll get any number of replys from Class 3 dealers, who, for the most part, are really nice people who will explain the process (and who will be happy to sell you their favorite AOW). Here's the location:
www.subguns.com/forum/wwwnfaad/
Good luck!